Transistors are key components of modern integrated circuits. To satisfy the requirements of increasingly faster speed, the drive currents of transistors need to be increasingly greater. To achieve this increase in performance, the gate lengths of transistors are constantly being scaled down. Scaling down the gate lengths leads to undesirable effects known as “short-channel effects,” in which the control of current flow by the gates is compromised. Among the short-channel effects are the Drain-Induced Barrier Lowering (DIBL) and the degradation of sub-threshold slope, both of which result in the degradation in the performance of transistors.
The use of a multi-gate transistor architecture may help the relief of short-channel effects. Fin Field-Effect Transistors (FinFET) were thus developed. To further increase electrostatic control of the channels, and, therefore, to reduce short-channel effects, transistors having wrapped-around gates were also developed, wherein the respective transistors are also referred to as gate-around transistors. A gate-around transistor, in addition to having gate portions on the top surface and sidewalls of a gate strip, also includes a gate portion underneath the semiconductor strip. This configuration, in which the gate electrode wraps around all sides of the channel, delivers a good electrostatic control of the channel, and hence, reduced short-channel effects.